Fountain solutions are used in the lithographic printing process to clean the surface of the lithographic printing plate, to replenish the desensitized area of the printing plate, and to continuously maintain the non-printing area of such plates water receptive or hydrophilic. Conventional liquid fountain solution concentrates are normally used but suffer from the disadvantage of being supplied in heavy drums. Alkaline and neutral dry powder formulations have been disclosed for use in lithographic printing of newspapers, magazines, and the like by Canale U.S. Pat. No. 4,187,029; 4,234,443; 4,340,509; and 4,374,036 which purport to allay the disadvantages of using liquid concentrates. Canale (U.S. Pat. No. 4,374,036) discloses a neutral dry powder fountain solution concentrate containing the following ingredients (all ingredients are solids unless where specified otherwise): tetrapotassium pyrophosphate, monosodium phosphate, tetrasodium EDTA, a sodium carboxymethyl cellulose, a water soluble polyethylene glycol, liquid silicone defoaming agents, liquid nonionic and anionic surfactants (e.g. Triton CF-32 and H-55 surfactants respectively), and Dowicil 75 biocide. This powder concentrate is typically dissolved in water in a ratio of about 27 lbs to 55 gallons of water to prepare a liquid fountain solution concentrate. The resulting concentrate is further diluted with water to prepare a press ready liquid fountain solution. Furthermore, Canale discloses an apparatus (U.S. Pat. No. 4,187,029) for dissolving a dry powder formulation with a predetermined amount of water, which also serves to maintain the solubility of the ingredients having different solubility characteristics by continuously recirculating the solution.
Ideally, a powdered fountain solution concentrate should be stable and free-flowing to facilitate transferring it to the mixer. Unfortunately, the above mentioned prior art compositions have a propensity to clump if either compressed, stored above 72.degree. F., or exposed to humid air, due in part to the following: 1) the presence of several liquid components in the formulation, 2) the presence of waxy or gummy polyethylene glycols in excess of 0.5% w/w in concentration, and 3) the absence of precautions to protect the formulation from high humidity conditions. All of these deleterious characteristics combine to make the use of this composition particularly disadvantageous. The manual addition of powder into the mixer may also cause spillage and worker exposure to irritating chemicals. Furthermore, practical difficulties are encountered in using the prior art powder concentrates because of the requirement of continuous recirculation to maintain its stability, and the apparent inability to prepare a highly concentrated fountain solution in excess of 0.7 lbs/gal.